Telescopic Cascode OTA Pole Shaping for Low-Power Timing
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Solution Overview
Problem
Low power operational transconductance amplifiers (OTAs) in wireless communication devices require high power consumption to meet timing requirements, particularly in delta-sigma analog-to-digital converters, which is inefficient and contradicts the need for low power consumption in mobile devices.
Innovation Solution
A single-stage telescopic cascode operational amplifier with a differential transistor pair and a capacitive element introducing a second frequency pole, reducing power consumption while maintaining performance by optimizing phase margin and response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the OTA uses large power consumption to meet timing requirements in delta-sigma ADC, then the timing requirement is satisfied, but power consumption increases
Solution Approach 1:
The patent introduces a second frequency pole (higher frequency than the first frequency pole) through a capacitive element coupled between the first and second nodes. This parameter change in the frequency response characteristics allows the OTA to achieve better phase margin (40-90 degrees) and meet timing requirements with reduced power consumption, resolving the contradiction between speed and power consumption
2Use of energy by moving object
If the OTA reduces power consumption, then power efficiency improves, but response time may deteriorate
Solution Approach 1:
By introducing the second frequency pole at a higher frequency than the first frequency pole, the patent shapes the frequency response to provide adequate phase margin (40-90 degrees) while maintaining fast response time. This parameter change in the transfer function allows low power consumption without sacrificing response time performance
3Device complexity
If the OTA uses a single-stage telescopic cascode structure, then device complexity is reduced, but phase margin control becomes difficult
Solution Approach 1:
The patent modifies the single-stage telescopic cascode OTA by introducing a capacitive element that creates a second frequency pole. This parameter change in the frequency response allows the simple single-stage structure to achieve controlled phase margin (40-90 degrees), resolving the contradiction between device complexity and phase margin control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces power consumption while maintaining performance, achieving a phase margin of approximately 40-90 degrees and improving response time, thus meeting the requirements of low power operation in mobile devices.
Implementation Method 1
A capacitive element is coupled between the first node and the second node. The response includes a second frequency pole based on the capacitive element.
Data Source
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AI summary
A method and an apparatus relating to an amplifier (e.g., an operational transconductance amplifier or OTA) are provided. The OTA includes a first node and a second node. The OTA further includes a differential transistor pair for receiving an input. The differential transistor pair is coupled to the first node and the second node. The OTA includes a pair of output nodes for outputting a response to the input. The response at the pair of output nodes includes a first frequency pole. A capacitive element is coupled between the first node and the second node. The response includes a second frequency pole based on the capacitive element. The second frequency pole is at a greater frequency than the first frequency pole.